Colon X-ray seen as effective at spotting cancer

**FILE** In this file photo released by the University of Wisconsin Medical School a 3-D image that was computer-generated from a series of X-rays taken by a CT scanner is seen. A study in Thursday's New England Journal of Medicine shows that "virtual colonoscopy" offers promise as an alternative to the more invasive conventional colonoscopy to detect suspicious growths. (AP Photo/ Courtesy of Dr. Perry J. Pickhardt/ University of Wisconsin Medical School, file)
— AP

**FILE** In this file photo released by the University of Wisconsin Medical School a 3-D image that was computer-generated from a series of X-rays taken by a CT scanner is seen. A study in Thursday's New England Journal of Medicine shows that "virtual colonoscopy" offers promise as an alternative to the more invasive conventional colonoscopy to detect suspicious growths. (AP Photo/ Courtesy of Dr. Perry J. Pickhardt/ University of Wisconsin Medical School, file)
/ AP

Back to the false alarms _ only one in four of those patients diagnosed with a growth actually had one, noted Dr. Robert Fletcher, a retired Harvard Medical School professor who wrote an editorial accompanying the study. He is a paid consultant for a company that makes a DNA screening test for colon cancer.

Some additional drawbacks to virtual colonoscopy:

_In about one in six of the patients, the X-ray found abnormalities outside the colon that led doctors to recommend additional testing or care. Some of those discoveries may be life-threatening, but others are not and investigation of them may prove expensive and hard on the patient, Fletcher wrote.

_The X-ray tests are not as good at colonoscopy at detecting flat growths on the colon wall that are more likely to be cancerous than the more familiar knobby polyps, according to other researchers.

_Virtual colonoscopies, currently recommended every five years, expose people to repeated doses of radiation. It's half the dose of a standard CT exam, but the cumulative effects are not yet known. Colonoscopy is only recommended every 10 years.

"These concerns do not rule out CT colonography as a screening test but they need to be considered," Fletcher wrote.

The study was not designed to look at whether the screenings prevented deaths.

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On the Net:

New England Journal:

(This version CORRECTS that colonoscopies usually involve sedation, not general anesthesia.))